Ashkenazi

Population genetics

Specific diseases

The Ashkenazi Jewish population has, like many other endogamous populations, a higher incidence of specific hereditary diseases. Genetic counseling and genetic testing are recommended for couples where both partners are of Ashkenazi ancestry. Some organizations, most notably Dor Yeshorim, organize screening programs to prevent homozygosity for the genes that cause these diseases. A large number of these diseases are neurological. See Jewish Genetics Center for more information on testing programmes.

Related Topics:
Hereditary - Disease - Genetic counseling - Genetic testing - Dor Yeshorim - Homozygosity - Gene

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Diseases with higher incidence in Ashkenazim include, in alphabetical order:

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• Bloom syndrome
• Breast cancer and ovarian cancer (due to higher distribution of BRCA1 and BRCA2).
• Canavan disease
• Colorectal cancer due to hereditary nonpolyposis colorectal cancer (HNPCC).
• Congenital adrenal hyperplasia (non-classical form)
• Crohn's disease (the NOD2/CARD15 locus appears to be implicated)
• Cystic fibrosis
• Familial dysautonomia (Riley-Day Syndrome)
• Fanconi anemia
• Gaucher's disease
• Hemophilia C
• Mucolipidosis IV
• Niemann-Pick disease
• Tay-Sachs disease
• Torsion dystonia
• Von Gierke disease

IQ

According to many studies, Ashkenazi Jews have among the highest average intelligence of any ethnic group as measured by IQ, leading East Asians, who also perform highly in IQ. This result is often used to explain some of the intellectual achievements of Ashkenazi Jews. For example, while Ashkenazi Jews represent 3% of the population of the United States, they have won 27% of the US Nobel Prizes in science, 25% of the ACM Turing Awards, and have accounted for more than half of world chess champions. Whether this difference in IQ and achievement is due entirely to a culture of study and vocational training (environment), or partially to a difference in genetic variables, is presently unknown and controversial. (See Race and intelligence)

Related Topics:
IQ - East Asian - Nobel Prize - ACM Turing Awards - World chess champions - Environment - Genetic - Race and intelligence

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"Natural History of Ashkenazi Intelligence"

See also Race and intelligence

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A controversial 2005 paper http://homepage.mac.com/harpend/.Public/AshkenaziIQ.jbiosocsci.pdf to be published in Cambridge's Journal of Biosocial Science, http://journals.cambridge.org/bin/bladerunner?REQUNIQ=1120424857&REQSESS=4209622&118000REQEVENT=&REQINT1=314478&REQAUTH=0 hypothesizes that European Jews' history of persecution created social selection for high intelligence, leaving a positive effect on the genetic component of their IQ.

Related Topics:
Selection - The genetic component

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The paper, by Gregory Cochran, Jason Hardy, and Henry Harpending http://www4.nationalacademies.org/nas/naspub.nsf/(urllinks)/NAS-58N4FF?opendocument of the University of Utah, notes that European Jews were forbidden to work in many of the common jobs of the middle-ages from AD800 to 1700, such as agriculture, and subsequently worked in high proportion in meritocratic, IQ-intensive jobs, such as finance and trade, some of which were forbidden to gentiles by the church. Cochran et al point out that those who performed better raised more children to adulthood, thus passing on their (higher-IQ) genes in greater proportion than those who performed poorer. The Jews rarely married outside of their faith, which created a reproductively isolated population, allowing, according to Cochran et al, a change in gene frequency to occur relatively rapidly in the 35 generations during these 9 centuries.

Related Topics:
Gregory Cochran - Henry Harpending - University of Utah - Meritocratic - IQ

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Cochran et al hypothesize that in this environment the social selection for intelligence was strong enough that mutations that created higher intelligence but created disease when inherited from both parents would still be selected for, which may be responsible for the unusual pattern of genetic diseases, such as Tay-Sachs and other sphingolipid diseases, that is found in the Ashkenazi population. Some of these diseases, for example, have been shown to correlate with high IQ, and others cause neurons to make relatively many connections with neighboring neurons.

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In a June 3 2005 New York Times article http://www.nytimes.com/2005/06/03/science/03gene.html, Cochran comments that he was drawn to the question when he noted that patients with torsion dystonia, relatively common in Ashkenazi Jews, had an average IQ of 122. The Harvard Psychologist Steven Pinker states that the results are bound to be controversial but hard to ignore. Geneticist Andrew Clark and mathematician Montgomery Slatkin comment that the study is far-fetched and unsupported by direct evidence.

Related Topics:
June 3 - 2005 - New York Times - Steven Pinker

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Alternative explanations along these lines include, for example, that for Jews to be socially successful in their peer group, expertise at Torah study has traditionally been an advantage (Murray 2003, Shafran 2005). Since the Enlightenment, those Jews lacking the intellectual skills for this endeavour may have been more prone to assimilate into general culture and leave the reproductively-isolated Jewish population.

Related Topics:
Torah study - The Enlightenment

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